The present invention relates generally to cooking apparatus and, in a preferred embodiment thereof, more particularly provides a large heating area deep fat cooking frypot in which the frypot cooking oil is heated utilizing a recirculating flow of heated gas.
Cooking oil frypots used to deep fry a variety of food products such as chicken, fish, french fries and the like are heated, among other known methods, by utilizing a throughflow of heated gas forced or drawn through exterior flow passages in thermal communication with wall portions of the frypot. The heating gas may be the combustion products emanating from an air-fuel burner, or may be electrically heated air. The conventional approach has been to simply flow the heating gas through the passageway system once--from its inlet to its outlet--and then exhaust the gas to atmosphere through an appropriate vent stack or the like. Not only does this approach waste potentially usable heating energy, but it also renders the desirably precise and uniform control of the cooking oil temperature within the cooking zone somewhat difficult to achieve.
As an example, particularly in larger volume frypots, the heating of only exterior wall portions of the frypot can result in rather significant cooking oil temperature variations between peripheral and central interior portions of the oil cooking zone within the frypot. Additionally, due to the fact that for a given frypot there is only a certain exterior wall area through which heat may be inwardly flowed, conventional "once through and dump" exterior heating schemes often lead to undesirably slow oil heating response times.
Another problem resulting from this conventional frypot oil heating technique is that of oil temperature "overshoot" when, for example, maximum heat input is used to bring the oil to its cooking temperature from a lower "standby" temperature. Unless the heat input is carefully controlled and timed (i.e., shut off or sharply reduced before the oil reaches its operating temperature), the oil temperature can significantly exceed the allowable maximum operating temperature thereof.
In order to diminish the oil heating response time in conventional fuel-fired frypots, great design care is used to assure that the flame emanating from the fuel-air burner contacts and extends along the maximum possible external surface area of the frypot to correspondingly maximize the combustion heat influx to the cooking oil. While this indeed accelerates the heating of the oil, it can also easily scorch the portion of the oil adjacent the interior cooking zone surface of the frypot when the temperature differential between the oil and the flame exceeds a critical maximum value. Great care must be taken to avoid this occurrence since it can ruin an entire batch of cooking oil. A complete solution to this conventional problem has proven to be rather elusive due to the very high flame temperatures typically involved.
In view of the foregoing, it is an object of the present invention to provide a deep fat cooking frypot having an improved oil heating system which eliminates or minimizes the above-mentioned and other problems, limitations and disadvantages typically associated with conventional frypot oil heating systems of the general type described.